TW440543B - Preparation of high purity lithium salts - Google Patents

Abstract

A process for preparing a high purity lithium salt from lithium carbonate comprises steps A to D as defined hereinbelow; (A) treating a mixture comprising lithium carbonatte and water by means of CO2 to obtain an aqueous mixture comprising lithium bicarbonate, (B) passing said aqueous mixture comprising lithium bicarbonate through an ion exchanger module, (C) precipitating lithium coarbonate from the ion exchange module treated lithium bicarbonate mixture obtained in step B, and (D) working up the precipitated lithium carbonate or converting the precipitated lithium carbonate into some other high purity lithium salt.

Description

^ 40543 V. Description of the invention α) The present invention relates to a method for preparing a high-purity lithium salt from lithium carbonate by feeding an aqueous mixture containing lithium argon carbonate into an ion exchanger module. With the development of lithium secondary batteries, high-purity lithium compounds have become more important. For this type of battery, it is necessary to use conductive salts such as Li P Fs or Li PF4. Such or similar conductive salts are usually made from lithium salts, such as lithium fluoride (L i F) or lithium gasified (LiCl), which are in turn obtained from lithium carbonate (Li2C03). In order to obtain a conductive salt from the above-mentioned lithium salt which can be used for the aforementioned purpose, the former must already have a relatively high purity. More specifically, it is desirable that the content of metal foreign ions be less than 1 ppm. Therefore, various methods for preparing high-purity lithium salts have been disclosed in the literature, especially those using lithium fluoride.

Stockbarger's method for preparing high-purity fluorinated fluorinated silicon is to produce single crystal L i F by regional melting. This method was disclosed in Gm e 1 i η 8th edition in 1960, 1!-¥ € 1'138 1 ^ 111} 1 €: [111 Vol. 6, pages 305-327 ° However, this type of lithium fluoride obtained for optical purposes is a single crystal type, the method is very complicated and expensive, so it is not suitable for the large amount of LiF produce. U.S. Patent No. 3 83 9 546 describes a method for preparing a high-purity alkali metal halide by reacting an alkali metal alkoxide with a gaseous halogen such as HC1 or SiCl4. This method is also complicated and expensive, especially the elemental alkali metal must be used as the starting material of the alkali metal alkoxide. DE-A 1 9 5 4 1 558 describes a method for purifying a lithium chloride solution, the focus of which is to remove unwanted sodium vapor components. This method uses a special procedure to evaporate to obtain a lithium gas solution with a yield of 2 99%, which can be substantially free of

^ 40543 V. Description of the invention (2) Sodium vaporization. 3 重量 ％。 Lithium gaseous solution obtained on the report contained sodium gaseous component less than 0.3% by weight. The NaC 1 content in the example is 0, 2%. A method for preparing a high-purity lithium salt by an ion exchanger is also generally known. In each case, however, lithium chloride solutions were treated (Hydro metal lurgy, 27 (1991), pages 317-325, US Patent Nos. 4 859 343 and 4 929 588). An object of the present invention is to provide a simple method for preparing a high-purity lithium salt, especially using lithium fluoride, lithium carbonate, and lithium gasified, which can meet the production on a large industrial scale. I have found that this purpose can be achieved by a method of preparing high-purity lithium from lithium carbonate, which method comprises steps A to D as defined below: A: treating a mixture containing lithium carbonate and water with CO 2 to obtain an aqueous solution containing lithium bicarbonate Mixture, B: The aqueous lithium hydrogen carbonate-containing mixture is passed through a group of ion exchange modules, C: Lithium carbonate is precipitated from the lithium hydrogen carbonate mixture treated by the ion exchange module obtained in step B, and D: After the precipitated lithium carbonate is sorted out, that is, it is completely separated, it can be optionally washed and dried with H20 or a solvent containing 1120, or the precipitated sodium carbonate can be converted into some other high-purity lithium salt. It is clear from the above that the present invention originates from lithium carbonate, and it is suspended in water, or in an aqueous solvent mixture with, for example, alcohol, ketone, or aldehyde, and then transferred to water-soluble lithium bicarbonate by the CO2 method The concentration of lithium / bicarbonate in the respective aqueous mixture ranges from about 0.5 to about 30% by weight, and more preferably ranges from about 3 to about 20% by weight.

Page 6 ^ 40543 V. Description of the invention (3) ~ "The generated aqueous bicarbonate chain mixture 'is then sent to the ion exchange template (step B) for processing. According to the present invention, this step β is preferably performed from about 10 to 2707, more preferably from about 20 to about 40 ° C. Steps A and B are preferably operated at a pressure above atmospheric pressure, so that a higher uhco3 concentration can be obtained. In step B, a general commercial ion exchange resin is used. Such an ion exchange resin preferably contains an organic polymer having an ionic active side chain such as a sulfur group or a hydroxyl group. In principle, according to the present invention, any polymer-based ion exchanger can be used, that is, not only a weak acid cation exchanger is available, but a strong acid can be applied to the ion exchanger module, including the above-mentioned positive: =: to: particles. Beads, granules, etc. (such as tubing). The polymer-based material particularly suitable for this type of ion exchanger is a copolymer of acetophenone and divinylbenzene, especially styrene-divinyl having an aminoalkenyl phosphate group or an iminodiacetic acid group. Benzene copolymer. Specific examples are: Lewatit ⑤ series resins, such as Lewat it⑥0C 1060 (AMP type), Lewatit ^ TP 208 (IDA type), Lewatit® E 304/88, Lewatit® TP 207, Lewatit ^ S 100; the brand name is Resins of the Amberlit e® series, such as A mber 1 it e⑧ IR 120, Amberlite® IRA 743; the trade name is Do we, such as dowex HCR; the trade name is Duolit, such as Duolite⑥C20, Duolite®

Φ4 05 4 3 V. Description of the invention (4) C467, Duolite® B346; and the brand name is imac @ 者 ’such as Imac® TMR, among which itg) series is more suitable. Particularly suitable for use are regeneration resins which contain relatively low sodium ions, or other very low sodium ion exchange resins. Details of the ion exchange resins suitable for use in the present invention are contained in Ullmann's Encycl. Of Industr. Chem., 5th edition, 14th volume, pages 393-459, the entire contents of which are incorporated herein. When the purity of lithium carbonate or lithium bicarbonate is very low, or it is desired to obtain a particularly high-purity lithium compound ', operation step B may be repeated 2 to 5 times, preferably 2 to 3 times. After step B, the solution is sent to step c, where the method of reprecipitating lithium carbonate out 'can be performed by heating to the boiling point of the solution and / or reducing the partial pressure. The step C temperature is usually in the range from about 80 to about 1000 ° C. The purified lithium carbonate is finally sent to the step]), which is here or directly sorted out, that is, completely separated, is preferably filtered, optionally washed with or containing 0 solvent, and then dried and / or re- Crystallize once, and then operate steps A to C 'or treat with a suitable reactant, such as aqueous hydrofluoric acid or hydrochloric acid' to convert it to the desired salt species. The lithium carbonate thus obtained usually has a foreign metal ion content of 10 ppm #, more preferably less than 5 ppm, particularly preferably less than 1 ppm, and a gas content of less than 30 ppm, and more preferably less than 10 ppm. Very good when less than 5 ppm. For example, to obtain lithium fluoride, the precipitated lithium carbonate can be suspended in water 'and then reacted with aqueous hydrofluoric acid' to form LiF. The output of LiF is solid

V. Description of the invention (5) state, which can be filtered and dried to a pure solid. C02 escapes as a gas. LiCl, UBr, Li2S04, LiN03, Li3P04, Li2C03 and other lithium salts can be prepared in the same way, such as LiBF4, LiC104, LiAsF6, LiCF3S03, LiC (CF3S02) 3, Li N (CF3S0.2) 2, L i N (C F3 CF2 S02) 2, LiN (S02F) 2, UA1C14, LiSiF6, LiSiF6, LiSbF5. The latter is particularly useful for conductive salts, while others in this regard are LiPFs, LiPF4 and 1 ^: 8? 4 in this order. In another specific example of the method of the present invention, it is possible to repeatedly dissolve the carbon dioxide in step A and precipitate the lithium carbonate in step C without repeating the effect of step B. This is when only a large amount of sodium and / or potassium is used. When it needs to be removed. In addition, the following sequence of steps can also be the method of the present invention: 1. Step A-Step B-Step C-Step A-Step C-Step D-; or 2. Step A-Step B-Step Step C-Step A- Step C-Step D; or 3. Step A-Step B-Step C-Step A-Step B-Step C-Step D. In another embodiment of the present invention, the method of the present invention is performed as follows: Step A: semi-continuous, that is, a suspension of water and Li2C03 is added at the beginning, and C02 is re-introduced; Step B: continuous; Step C With D: batch operation. Based on the above, the method of the present invention has its special advantages. It can effectively remove not only alkali metal cations, especially sodium ions, but also other polyvalent cations, such as alkaline earth metals and transition metal ions. The concentration of sodium in L i2 C 03 is reduced to more than 400 times; and impurities such as calcium, magnesium, iron, and / or aluminum caused by polyvalent ions are substantially complete.

44〇543 V. Description of the invention (6) All were removed by the ion exchanger treatment in step β. In addition, the resulting product is essentially gas-free. In the following, a specific example of the present invention will be described more specifically by way of example. (Preparation and Purification of Example Li F) First, take 100 g of Li2C03 (experimental grade) (1353㈣ "and other ㈣g of distilled water into a 21 glass bottle and weigh in. Stir at room temperature (21 ° C) and pour in ⑶2 6 Hours until the number of L is dissolved. —3 The resulting solution is filtered and sent under pressure to the ion exchanger bed regenerated through Lewatlt © Tp 207 (100ml), and then washed with water. This Lewati® TP 207 The dose was 400 ml / h. The solution obtained through the ion exchanger bed was heated and boiled under reflux to convert lithium bicarbonate (except CO 2) into lithium carbonate and precipitate. The residue was washed with water, dried at 3, leaving 69.6 g of dry lithium carbonate. Dry = 58.22 g (0.7 88 mol) of this amount was once again mixed with water (110 g) and 5 Absorb the C 02 gas and dissolve it again. The yield is equivalent to 69. 6%, which is based on the amount of lithium carbonate used, 遽 'output and 78.8 g of 40% by weight hydrofluoric acid (1.5 7 6 mol hf)> Seen to discharge CO2 to precipitate lithium fluoride. Adjust the pH to 7.5 with ammonia solution This batch 'filters out the residue It was washed with water and dried at 300 ° C. Too long, about 39 g of lithium fluoride was obtained. After treatment with the ion exchanger, the lithium I, Li, i, and ^ coin carbonic acid was set as the base leaf, which is equivalent to 95 . 5% yield.

Page 10 44〇543 V. Description of the invention (7) Therefore, based on the amount of Li 2 C03 used, the final yield of Li F is 6 6.4% a. It is related to the purity of L 12 C 03 and L 1 F The results are listed in the following table.

Li2C03 dosage [mg / kg] Li2C03 First sinking source [mg / kg] LiF [mg / kg] Li foreign metal ion concentration ratio per mol of Li before / after first precipitation Al foreign metal ion concentration aluminum 7 < 1 < 1 > 7 calcium 60 < 1 about 1 > 60 iron 3 < 1 < 1 > 3 potassium 40 < 1 < 1 > 40 magnesium 25 < 1 < 1 > 25 sodium 480 about 1 < 1 480 chlorine 55 < 5 < 5 55

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Claims (1)

Amend VIII—Case No. 8 Paste 201 VI. Applying for φ Patent 1. A to D steps defined by carbonic acid: A: treating a mixture containing lithium carbonate and water with C02 to obtain an aqueous mixture containing a hydrogen carbonate chain, B: let the The aqueous mixture containing lithium bicarbonate passes through a group of ion exchanger modules, C: Lithium carbonate is precipitated from the lithium bicarbonate mixture processed by the ion exchanger module obtained in step B, and D: the precipitated lithium carbonate is treated , Or transform the precipitated lithium carbonate into some other high-purity lithium salt. 2. The method according to item 1 of the patent application scope, wherein the high-purity lithium salt is lithium chloride, lithium fluoride, lithium bromide, lithium sulfate, lithium nitrate, lithium phosphate, or lithium carbonate. 3. The method according to item 1 of the patent application scope, wherein the high-purity lithium salt has a foreign metal ion content of less than 1 ppm. 4. The method of item 1 in the scope of patent application, wherein step B is repeated. 5. If the method of applying for the first item of the patent scope, it is performed in any of the following order from 1 to 3: 1. Step A-Step B-Step C-Step A-Step C-Step D-; or. 2 Step A-Step B-Step B-Step C-Step A-Step C-Step D; or 3. Step A-Step Step C-Step A-Step B-Step C-Step D. 6. The method according to any one of claims 1 to 5, wherein the ion O: \ 57 \ 57352.ptc Page 1 2000.07. 27.012 440543 O: \ 57 \ 57352.ptc Page 2 2000.07. 27.013 Correction VIII—Case No. 8 Paste 201 VI. Applying for φ Patent 1. A to D steps defined by carbonic acid: A: treating a mixture containing lithium carbonate and water with C02 to obtain an aqueous mixture containing a hydrogen carbonate chain, B: let the The aqueous mixture containing lithium bicarbonate passes through a group of ion exchanger modules, C: Lithium carbonate is precipitated from the lithium bicarbonate mixture processed by the ion exchanger module obtained in step B, and D: the precipitated lithium carbonate is treated , Or transform the precipitated lithium carbonate into some other high-purity lithium salt. 2. The method according to item 1 of the patent application scope, wherein the high-purity lithium salt is lithium chloride, lithium fluoride, lithium bromide, lithium sulfate, lithium nitrate, lithium phosphate, or lithium carbonate. 3. The method according to item 1 of the patent application scope, wherein the high-purity lithium salt has a foreign metal ion content of less than 1 ppm. 4. The method of item 1 in the scope of patent application, wherein step B is repeated. 5. If the method of applying for the first item of the patent scope, it is performed in any of the following order from 1 to 3: 1. Step A-Step B-Step C-Step A-Step C-Step D-; or. 2 Step A-Step B-Step B-Step C-Step A-Step C-Step D; or 3. Step A-Step Step C-Step A-Step B-Step C-Step D. 6. The method according to any one of claims 1 to 5, wherein the ion O: \ 57 \ 57352.ptc Page 1 2000.07. 27.012